Phase 1 study of ARQ 761, a ß-lapachone analogue that promotes NQO1-mediated programmed cancer cell necrosis.

BACKGROUND: NAD(P)H:quinone oxidoreductase 1 (NQO1) is a two-electron oxidoreductase expressed in multiple tumour types. ARQ 761 is a ß-lapachone (ß-lap) analogue that exploits the unique elevation of NQO1 found in solid tumours to cause tumour-specific cell death. METHODS: We performed a 3+3 dose escalation study of 3 schedules (weekly, every other week, 2/3 weeks) of ARQ 761 in patients with refractory advanced solid tumours. Tumour tissue was analysed for NQO1 expression. After 20 patients were analysed, enrolment was restricted to patients with NQO1-high tumours (H-score ≥ 200). RESULTS: A total of 42 patients were treated. Median number of prior lines of therapy was 4. Maximum tolerated dose was 390 mg/m2 as a 2-h infusion every other week. Dose-limiting toxicity was anaemia. The most common treatment-related adverse events were anaemia (79%), fatigue (45%), hypoxia (33%), nausea (17%), and vomiting (17%). Transient grade 3 hypoxia, reflecting possible methemoglobinaemia, occurred in 26% of patients. Among 32 evaluable patients, best response was stable disease (n = 12); 6 patients had tumour shrinkage. There was a trend towards improved efficacy in NQO1-high tumours (P = 0.06). CONCLUSIONS: ARQ 761 has modest single-agent activity, which appears associated with tumour NQO1 expression. Principal toxicities include anaemia and possible methemoglobinaemia.

Quantification of myo-inositol, 1,5-anhydro- D-sorbitol, and D-chiro-inositol using high-performance liquid chromatography with electrochemical detection in very small volume clinical samples.

Inositol is a six-carbon sugar alcohol and is one of nine biologically significant isomers of hexahydroxycyclohexane. Myo-inositol is the primary biologically active form and is present in higher concentrations in the fetus and newborn than in adults. It is currently being examined for the prevention of retinopathy of prematurity in newborn preterm infants. A robust method for quantifying myo-inositol (MI), D-chiro-inositol (DCI) and 1,5-anhydro- D-sorbitol (ADS) in very small-volume (25 µL) urine, blood serum and/or plasma samples was developed. Using a multiple-column, multiple mobile phase liquid chromatographic system with electrochemical detection, the method was validated with respect to (a) selectivity, (b) accuracy/recovery, (c) precision/reproducibility, (d) sensitivity, (e) stability and (f) ruggedness. The standard curve was linear and ranged from 0.5 to 30 mg/L for each of the three analytes. Above-mentioned performance measures were within acceptable limits described in the Food and Drug Administration's Guidance for Industry: Bioanalytical Method Validation. The method was validated using blood serum and plasma collected using four common anticoagulants, and also by quantifying the accuracy and sensitivity of MI measured in simulated urine samples recovered from preterm infant diaper systems. The method performs satisfactorily measuring the three most common inositol isomers on 25 µL clinical samples of serum, plasma, milk, and/or urine. Similar performance is seen testing larger volume samples of infant formulas and infant formula ingredients. MI, ADS and DCI may be accurately tested in urine samples collected from five different preterm infant diapers if the urine volume is greater than 2-5 mL.

Ethambutol pharmacokinetic variability is linked to body mass in overweight, obese, and extremely obese people.

We conducted a prospective study of 18 adult volunteers (male-to-female ratio of 1) whose body mass index fell into categories of <25, 25 to 40, or >40 kg/m(2), who received a single oral dose of 1,600 mg ethambutol. Only individuals with normal renal function were recruited. The minimum body mass (M) was 45.6 kg, the median was 90.8 kg, and the maximum weight was 160.4 kg. Ethambutol pharmacokinetics were best described by a two-compartment model. Inclusion of weight as a covariate dramatically improved the model, with a relative likelihood approaching infinity. The typical clearance was 42.6 liters/h. Ethambutol systemic clearance was proportional to (M/45.6)(3/4) and thus obeyed fractal geometry-based laws. This means that the area under the concentration-time curve (AUC) actually decreased for obese patients compared to that for leaner patients, reducing chances of concentration-dependent toxicity. On the other hand, such reduced AUCs could lead to therapy failure. Thus, new and individualized ethambutol dosing regimens need to be designed for obese and extremely obese patients.

Ribavirin improves early responses to peginterferon through improved interferon signaling.

BACKGROUND & AIMS: The therapeutic mechanisms of ribavirin for hepatitis C are unclear. Microarray analyses have shown that ribavirin increases induction of interferon-stimulated genes. We evaluated viral kinetics, serum cytokine expression, and viral mutagenesis during early stages of peginterferon therapy with and without ribavirin. METHODS: Fifty patients with chronic hepatitis C virus (HCV) infection genotype 1 were randomly assigned to groups that were given peginterferon alpha-2a, with or without ribavirin, for 4 weeks; all patients then received an additional 44 weeks of combination therapy. First- and second-phase viral kinetics were evaluated. Serum levels of interferon-gamma-inducible protein-10 (IP10), monokine induced by interferon-gamma, and monocyte chemoattractant protein 1 were quantified as measures of the interferon-stimulated genes response. NS5A and NS5B were partially sequenced, and mutation rates were calculated. RESULTS: The first-phase decrease in HCV RNA was similar between groups. Patients who received ribavirin had a more rapid second-phase decrease, compared with patients who did not receive ribavirin-particularly those with an adequate first-phase decrease (0.61 vs 0.35 log10 IU/mL/week; P = .018). At 12 hours, fold induction of serum IP10 was higher in patients given the combination therapy than those given peginterferon only (7.6- vs 3.8-fold; P = .01); however, the difference was greatest in patients with an adequate first-phase decrease in HCV RNA. IP10-induction correlated with first- and second-phase kinetics and with ribavirin serum concentrations on day 3. HCV mutation rates were similar between groups. CONCLUSIONS: Ribavirin improves the kinetics of the early response to therapy in patients with an adequate initial response to peginterferon. Induction of interferon-stimulated cytokines correlates with viral kinetics following ribavirin therapy, suggesting that ribavirin promotes interferon signaling.

Pharmacokinetics of oseltamivir in breast milk and maternal plasma.

OBJECTIVE: Women in the postpartum period are at high risk for complications from influenza. Pharmacokinetic data of oseltamivir phosphate in postpartum women, however, are lacking. STUDY DESIGN: Seven healthy patients within 48 hours of delivery were recruited. Each woman received 75 mg of oseltamivir phosphate. Plasma and breast milk samples were obtained at times 0, 0.5, 1, 2, 4, 8, 12, and 24 hours after the first dose. The samples were analyzed for oseltamivir and oseltamivir carboxylate levels. Using a noncompartmental model, area under the curve (AUC), maximum concentration (C(max)), time to maximum concentration, and half-life were estimated. RESULTS: Oseltamivir phosphate and oseltamivir carboxylate were found in breast milk, although later and in lower levels than that found in plasma. The C(max) and AUC 0-24 was higher for the active metabolite than for the prodrug in both plasma and breast milk. CONCLUSION: Oseltamivir carboxylate was present in breast milk but in concentrations significantly lower than considered therapeutic in infants.

Pharmacokinetics of oseltamivir according to trimester of pregnancy.

The purpose of this study was to determine pharmacokinetic parameters for oseltamivir in all trimesters of pregnancy. Thirty pregnant women, 10 per trimester, who were receiving oseltamivir phosphate (75 mg) were recruited to study first-dose pharmacokinetics. Plasma samples were obtained at 0, 0.5, 1, 2, 4, 8, and 12 hours after the first dose. Samples were analyzed for oseltamivir and oseltamivir carboxylate levels. With the use of a noncompartmental model, we estimated the area-under-the-curve, maximum concentration, time-to-maximum concentration, and half-life. There were no significant differences in the pharmacokinetics of oseltamivir by trimester, except for an increased half-life in the first trimester for oseltamivir phosphate and an increased maximum concentration in the third trimester for oseltamivir carboxylate. The levels of oseltamivir carboxylate that were observed were within the range that was needed to achieve inhibitory concentrations at 50% for pandemic H1N1. The pharmacokinetics of oseltamivir does not change significantly according to trimester of pregnancy.

Concentration-dependent Early Antivascular and Antitumor Effects of Itraconazole in Non-Small Cell Lung Cancer.

PURPOSE: Itraconazole has been repurposed as an anticancer therapeutic agent for multiple malignancies. In preclinical models, itraconazole has antiangiogenic properties and inhibits Hedgehog pathway activity. We performed a window-of-opportunity trial to determine the biologic effects of itraconazole in human patients. EXPERIMENTAL DESIGN: Patients with non-small cell lung cancer (NSCLC) who had planned for surgical resection were administered with itraconazole 300 mg orally twice daily for 10-14 days. Patients underwent dynamic contrast-enhanced MRI and plasma collection for pharmacokinetic and pharmacodynamic analyses. Tissues from pretreatment biopsy, surgical resection, and skin biopsies were analyzed for itraconazole and hydroxyitraconazole concentration, and vascular and Hedgehog pathway biomarkers. RESULTS: Thirteen patients were enrolled in this study. Itraconazole was well-tolerated. Steady-state plasma concentrations of itraconazole and hydroxyitraconazole demonstrated a 6-fold difference across patients. Tumor itraconazole concentrations trended with and exceeded those of plasma. Greater itraconazole levels were significantly and meaningfully associated with reduction in tumor volume (Spearman correlation, -0.71; P = 0.05) and tumor perfusion (Ktrans; Spearman correlation, -0.71; P = 0.01), decrease in the proangiogenic cytokines IL1b (Spearman correlation, -0.73; P = 0.01) and GM-CSF (Spearman correlation, -1.00; P < 0.001), and reduction in tumor microvessel density (Spearman correlation, -0.69; P = 0.03). Itraconazole-treated tumors also demonstrated distinct metabolic profiles. Itraconazole treatment did not alter transcription of GLI1 and PTCH1 mRNA. Patient size, renal function, and hepatic function did not predict itraconazole concentrations. CONCLUSIONS: Itraconazole demonstrates concentration-dependent early antivascular, metabolic, and antitumor effects in patients with NSCLC. As the number of fixed dose cancer therapies increases, attention to interpatient pharmacokinetics and pharmacodynamics differences may be warranted.

Effects of atazanavir/ritonavir or fosamprenavir/ritonavir on the pharmacokinetics of rosuvastatin.

BACKGROUND: Rosuvastatin (RSV) is a potent statin with a lower potential for drug interactions. However, recent data have revealed unexpected increases in RSV concentrations with lopinavir/ritonavir. The objective is to study the pharmacokinetic interaction of RSV with atazanavir/ritonavir (ATV/RTV) or fosamprenavir/ritonavir (FPV/RTV). METHODS: In a prospective pharmacokinetic drug interaction study, six HIV-seronegative, healthy adult volunteers received single 10-mg doses of RSV at baseline and after 6 days of ATV/RTV and FPV/RTV, with 6-day washout periods. Plasma concentrations of RSV and its metabolites, N-desmethyl-RSV and RSV-lactone, were measured by using a internally validated tandem mass spectrometric (LC-MS/MS) method over 24 hours. RESULTS: Compared to baseline, the area under the plasma concentration-time curve (AUC 0-24h) and maximum plasma concentration (Cmax) of RSV increased by 213% and 600%, respectively, and the time to reach Cmax was shorter (1.75 h vs. 2.91 h) when given with ATV/RTV (P < 0.05). However, coadministration with FPV/RTV did not significantly affect the pharmacokinetics of RSV. The AUC 0-24h of N-desmethyl-RSV was not significantly affected by either combinations, but that of RSV-lactone increased (P < 0.05) by 61% and 76% after coadministration with ATV/RTV and FPV/RTV, respectively. CONCLUSION: ATV/RTV significantly increases the plasma concentrations of rosuvastatin, most likely by increasing rosuvastatin's oral bioavailability. Dose limitations of RSV with ATV/RTV may be needed.

COPD: clinical significance of early diagnosis.

OBJECTIVE: To explain the differential diagnosis of chronic obstructive pulmonary disease (COPD) and how COPD can be distinguished in patients who present with complaints of dyspnea, (shortness of breath on exertion), with the goal of improving earlier diagnosis. SUMMARY: It is important to differentiate COPD from other diagnoses when adult patients present with dyspnea. There are several key diagnostic indicators for COPD, including, most notably, a history of smoking and objective lung-function measurements. COPD remains an underdiagnosed disease, chiefly in its milder and more treatable form. The Global Initiative for Chronic Obstructive Lung Disease (GOLD)- defined standards for COPD management consist of 4 components: (1) assess and monitor disease, (2) reduce risk factors, (3) manage stable COPD through education and nonpharmacologic and pharmacologic means, and (4) manage exacerbations. CONCLUSION: Updated standards for diagnosis and treatment-targeted pharmacologic agents have provided physicians and health care workers with more specific and targeted treatment modalities for early detection and treatment of this progressive disease. Early detection and more accurate diagnosis are key in improving outcomes and altering the progression of the disease.

Treatment of active pulmonary tuberculosis in adults: current standards and recent advances. Insights from the Society of Infectious Diseases Pharmacists.

Tuberculosis is a global pandemic, with 9 million new cases of the disease and approximately 2 million deaths each year. More than 98% of patients treated for tuberculosis in the United States between 1993 and 2007 had drug-susceptible strains. The standard treatment regimen for drug-susceptible tuberculosis has not changed in decades and was developed on the basis of empiric observations of different treatment regimens. Only recently has the veracity of the scientific basis for standard therapy been examined. The backbone of therapy is still isoniazid, rifampin, and pyrazinamide, although fluoroquinolones are being investigated as a replacement for isoniazid. Recent population pharmacokinetic studies have demonstrated the importance of individualized dosing of isoniazid, pyrazinamide, and rifampin. Isoniazid serum clearance differs depending on the patient's number of N-acetyltransferase 2 gene *4 (NAT2*4) alleles. Pyrazinamide serum clearance has been shown to increase with increases in body weight. Rifampin's volume of distribution, clearance, and absorption have wide between-patient and within-patient variability. Microbial pharmacokinetic-pharmacodynamic (PK-PD) indexes and targets to optimize microbial killing and minimize resistance have been identified for rifampin, isoniazid, pyrazinamide, and the fluoroquinolones. These PK-PD indexes suggest that different doses and dosing schedules than those currently recommended could optimize therapy and perhaps shorten duration of therapy. Efflux pump inhibition is also being investigated to enhance first-line antituberculosis drug therapy. Comorbid conditions such as diabetes mellitus and genetically determined iron overload syndromes have been associated with significantly worse patient outcomes. Therapy for these and other patient groups needs further improvement. These patient factors, the covariates for pharmacokinetic variability, and PK-PD factors suggest the need to individualize therapy for patients with tuberculosis in order to optimize outcomes and reduce the duration of therapy.